Study of suspension settling: An approach to determine suspension classification and particle interactions

Abstract : The properties of mineral suspensions do not evolve linearly with particle mass fraction. For some critical concentrations these properties are abruptly modified due to a change of relative interparticle interaction force prevalence. Using kaolin and glass beads as model materials, physico-chemical stability and rheological measurement have been carried out in order to propose a global and discriminant parameter enabling the nature of particle interactions to be identified. Different types of suspensions were studied namely: diluted suspensions, concentrated suspensions and solid suspensions. Physico-chemical stability, studied by optical dispersion analysis (Turbiscan MA 2000) enables the clarification rate to be measured and to propose a new global parameter, the “phase separation index”. In addition, rheological analysis was realized by the means of viscous flow measurement. Behaviour of solid suspensions is satisfactorily described by Oswald de Waele power law in the whole range of concentration studied which tends to demonstrate that the interactions remains the same in this range.